\uc548\ub155\ud558\uc138\uc694! \uc774\ubc88 \ud3ec\uc2a4\ud305\uc5d0\uc11c\ub294 \uc790\ubc14\uc2a4\ud06c\ub9bd\ud2b8\ub85c \ucf54\ub529\ud14c\uc2a4\ud2b8\ub97c \uc900\ube44\ud558\ub294 \uc5ec\ub7ec\ubd84\ub4e4\uc744 \uc704\ud574 ‘\uc8fc\ubabd\uc758 \uba85\ub839’\uc774\ub77c\ub294 \uc8fc\uc81c\ub97c \uac00\uc9c0\uace0 \uc54c\uace0\ub9ac\uc998 \ubb38\uc81c\ub97c \ud480\uc5b4\ubcf4\uaca0\uc2b5\ub2c8\ub2e4. \uc774 \uacfc\uc815\uc5d0\uc11c \ubb38\uc81c\ub97c \uc774\ud574\ud558\uace0, \uc811\uadfc\ud558\ub294 \ubc29\ubc95, \ucf54\ub4dc \uad6c\ud604 \ubc0f \uc2dc\uac04 \ubcf5\uc7a1\ub3c4 \ubd84\uc11d\uae4c\uc9c0 \uc790\uc138\ud788 \uc124\uba85\ud560 \uac83\uc785\ub2c8\ub2e4.<\/p>\n
\uc8fc\ubabd\uc740 \ud55c\uaca8\uc6b8\uc5d0\ub3c4 \ubd88\uad6c\ud558\uace0 \uc790\uc2e0\uc758 \ubd80\ud558\ub4e4\uc5d0\uac8c \uba85\ub839\uc744 \ub0b4\ub838\uc2b5\ub2c8\ub2e4. \uadf8\uc758 \uba85\ub839\uc740 \ub2e4\uc74c\uacfc \uac19\uc740 \ud615\ud0dc\ub85c \uc8fc\uc5b4\uc9d1\ub2c8\ub2e4:<\/p>\n
\uc774 \ubb38\uc81c\uc5d0\uc11c \uc6b0\ub9ac\ub294 \ud2b8\ub9ac\uc758 \uacbd\ub85c\uac00 \ubb34\uc5c7\uc778\uc9c0, \uadf8\ub9ac\uace0 \uc5b4\ub5bb\uac8c \ud0d0\uc0c9\ud560 \uac83\uc778\uc9c0\ub97c \uba85\ud655\ud788 \uc774\ud574\ud574\uc57c \ud569\ub2c8\ub2e4. \uacbd\ub85c\ub780 \ub8e8\ud2b8\uc5d0\uc11c \ub9ac\ud504 \ub178\ub4dc\uae4c\uc9c0 \uc774\ub3d9\ud558\ub294 \ubaa8\ub4e0 \ub178\ub4dc\uc758 \uc9d1\ud569\uc744 \uc758\ubbf8\ud569\ub2c8\ub2e4.<\/p>\n
\n{\n \"root\": {\n \"value\": 1,\n \"left\": {\n \"value\": 2,\n \"left\": null,\n \"right\": {\n \"value\": 3,\n \"left\": null,\n \"right\": null\n }\n },\n \"right\": {\n \"value\": 4,\n \"left\": null,\n \"right\": null\n }\n },\n \"x\": 1\n}\n<\/pre>\n\ucd9c\ub825 \ud615\uc2dd<\/h2>\n
\uc8fc\uc5b4\uc9c4 \uc774\uc9c4 \ud2b8\ub9ac\uc5d0\uc11c \uc22b\uc790 x\uc758 \uac1c\uc218\ub97c \ud3ec\ud568\ud558\ub294 \ubaa8\ub4e0 \uacbd\ub85c\uc758 x \uac1c\uc218\uc758 \ud569\uc744 \ubc18\ud658\ud55c\ub2e4.<\/p>\n
\n{\n \"result\": 2\n}\n<\/pre>\n\ubb38\uc81c \uc811\uadfc\ubc95<\/h2>\n
\uc774 \ubb38\uc81c\ub97c \ud480\uae30 \uc704\ud574\uc11c\ub294 DFS(Depth-First Search) \uc54c\uace0\ub9ac\uc998\uc744 \uc0ac\uc6a9\ud560 \uac83\uc785\ub2c8\ub2e4. \uc774\uc9c4 \ud2b8\ub9ac\ub97c \uae4a\uc774 \uc6b0\uc120\uc73c\ub85c \ud0d0\uc0c9\ud558\uba74\uc11c \uacbd\ub85c\ub97c \ub530\ub77c `x`\ub97c \uc138\uc5b4 \ub098\uac00\ub294 \ubc29\uc2dd\uc785\ub2c8\ub2e4.<\/p>\n
1\ub2e8\uacc4: \ud2b8\ub9ac \ud0d0\uc0c9<\/h3>\n
\uc6b0\uc120 \ud2b8\ub9ac\ub97c \ud0d0\uc0c9\ud560 \uc218 \uc788\ub294 \uc7ac\uadc0 \ud568\uc218\ub97c \uc791\uc131\ud569\ub2c8\ub2e4. \uc774 \ud568\uc218\ub294 \ud604\uc7ac \ub178\ub4dc, \ud604\uc7ac \uacbd\ub85c\uc5d0 \ud3ec\ud568\ub41c x\uc758 \uac1c\uc218, \uadf8\ub9ac\uace0 \uacb0\uacfc\ub97c \uc800\uc7a5\ud560 \ubcc0\uc218\ub97c \uc778\uc790\ub85c \ubc1b\uc2b5\ub2c8\ub2e4.<\/p>\n
2\ub2e8\uacc4: \uacbd\ub85c \uc800\uc7a5 \ubc0f \uc870\uac74 \ud655\uc778<\/h3>\n
\ub178\ub4dc\uac00 \ub9ac\ud504 \ub178\ub4dc\uc778\uc9c0 \ud655\uc778\ud558\uace0, \ub9ac\ud504 \ub178\ub4dc\uc5d0 \ub3c4\ub2ec\ud588\uc744 \ub54c \uacbd\ub85c\uc5d0 \ud3ec\ud568\ub41c x\uc758 \uac1c\uc218\ub97c \uacb0\uacfc \ubcc0\uc218\uc5d0 \ub354\ud569\ub2c8\ub2e4. \uadf8\ub9ac\uace0 \ud604\uc7ac \ub178\ub4dc\uac00 \ub9ac\ud504\uac00 \uc544\ub2d0 \uacbd\uc6b0 \uc67c\ucabd \ubc0f \uc624\ub978\ucabd \uc790\uc2dd \ub178\ub4dc\ub97c \uc7ac\uadc0\uc801\uc73c\ub85c \ud0d0\uc0c9\ud569\ub2c8\ub2e4.<\/p>\n
3\ub2e8\uacc4: \uc2dc\uac04 \ubcf5\uc7a1\ub3c4 \ubd84\uc11d<\/h3>\n
\uc774 \uc54c\uace0\ub9ac\uc998\uc758 \uc2dc\uac04 \ubcf5\uc7a1\ub3c4\ub294 O(n)\uc785\ub2c8\ub2e4. \ud2b8\ub9ac\uc758 \ubaa8\ub4e0 \ub178\ub4dc\ub97c \ud55c \ubc88\uc529 \ubc29\ubb38\ud558\uae30 \ub54c\ubb38\uc785\ub2c8\ub2e4.<\/p>\n
\ucf54\ub4dc \uad6c\ud604<\/h2>\n\nfunction countXPaths(root, x) {\n let totalPathsCount = 0;\n\n function dfs(node, currentCount) {\n if (node === null) {\n return;\n }\n\n \/\/ \ud604\uc7ac \ub178\ub4dc\uc758 \uac12\uc744 \ud655\uc778\n let newCount = currentCount + (node.value === x ? 1 : 0);\n\n \/\/ \ub9ac\ud504 \ub178\ub4dc\uc778\uc9c0 \ud655\uc778\n if (node.left === null && node.right === null) {\n totalPathsCount += newCount;\n return;\n }\n\n \/\/ \uc67c\ucabd\uacfc \uc624\ub978\ucabd \uc790\uc2dd \ub178\ub4dc \ud0d0\uc0c9\n dfs(node.left, newCount);\n dfs(node.right, newCount);\n }\n\n dfs(root, 0);\n return { result: totalPathsCount };\n}\n<\/code><\/pre>\n\ud14c\uc2a4\ud2b8 \ucf00\uc774\uc2a4<\/h2>\n
\uc774\uc81c \ub2e4\uc591\ud55c \ud14c\uc2a4\ud2b8 \ucf00\uc774\uc2a4\ub97c \ub9cc\ub4e4\uc5b4 \uc6b0\ub9ac\uac00 \uc791\uc131\ud55c \ucf54\ub4dc\uac00 \uc608\uc0c1\ub300\ub85c \uc791\ub3d9\ud558\ub294\uc9c0 \ud655\uc778\ud574\ubcf4\uaca0\uc2b5\ub2c8\ub2e4.<\/p>\n
\n\/\/ 1\ubc88 \ud14c\uc2a4\ud2b8 \ucf00\uc774\uc2a4\nconst testCase1 = {\n root: {\n value: 1,\n left: {\n value: 2,\n left: null,\n right: {\n value: 1,\n left: null,\n right: null\n }\n },\n right: {\n value: 4,\n left: null,\n right: null\n }\n },\n x: 1\n};\nconsole.log(countXPaths(testCase1.root, testCase1.x)); \/\/ \ucd9c\ub825: { result: 2 }\n\n\/\/ 2\ubc88 \ud14c\uc2a4\ud2b8 \ucf00\uc774\uc2a4\nconst testCase2 = {\n root: {\n value: 2,\n left: {\n value: 1,\n left: null,\n right: null\n },\n right: {\n value: 1,\n left: {\n value: 3,\n left: null,\n right: null\n },\n right: null\n }\n },\n x: 1\n};\nconsole.log(countXPaths(testCase2.root, testCase2.x)); \/\/ \ucd9c\ub825: { result: 3 }\n\n\/\/ 3\ubc88 \ud14c\uc2a4\ud2b8 \ucf00\uc774\uc2a4\nconst testCase3 = {\n root: {\n value: 5,\n left: {\n value: 1,\n left: {\n value: 1,\n left: null,\n right: null\n },\n right: {\n value: 2,\n left: null,\n right: null\n }\n },\n right: {\n value: 7,\n left: null,\n right: null\n }\n },\n x: 1\n};\nconsole.log(countXPaths(testCase3.root, testCase3.x)); \/\/ \ucd9c\ub825: { result: 2 }\n<\/code><\/pre>\n\uacb0\ub860<\/h2>\n
\uc774\ubc88 \ud3ec\uc2a4\ud305\uc5d0\uc11c\ub294 \uc8fc\ubabd\uc758 \uba85\ub839\uc774\ub77c\ub294 \uc54c\uace0\ub9ac\uc998 \ubb38\uc81c\ub97c \ud1b5\ud574 \uae4a\uc774 \uc6b0\uc120 \ud0d0\uc0c9\uacfc \uc7ac\uadc0\ud568\uc218\uc758 \uac1c\ub150\uc744 \uc774\ud574\ud558\uace0 \uad6c\ud604\ud574\ubcf4\uc558\uc2b5\ub2c8\ub2e4. \ub2e4\uc591\ud55c \ud14c\uc2a4\ud2b8 \ucf00\uc774\uc2a4\ub97c \ud1b5\ud574 \ucf54\ub4dc\uc758 \uc2e0\ub8b0\uc131\uc744 \ub192\uc77c \uc218 \uc788\uc5c8\uc73c\uba70, \uac01 \ub2e8\uacc4\ubcc4\ub85c \ubb38\uc81c\ub97c \ud574\uacb0\ud558\ub294 \ubc29\ubc95\uc744 \uccb4\uacc4\uc801\uc73c\ub85c \uc815\ub9ac\ud588\uc2b5\ub2c8\ub2e4.<\/p>\n
\ucf54\ub529 \ud14c\uc2a4\ud2b8\ub97c \uc900\ube44\ud558\ub294 \uacfc\uc815\uc5d0\uc11c \ubb38\uc81c\ub97c \uc811\uadfc\ud558\ub294 \uc0ac\uace0\ubc29\uc2dd\uacfc \uad6c\ud604 \ub2a5\ub825\uc740 \ub9e4\uc6b0 \uc911\uc694\ud569\ub2c8\ub2e4. \uc9c0\uc18d\uc801\uc73c\ub85c \uc5f0\uc2b5\ud558\uba74\uc11c \uc774\ub7ec\ud55c \ubb38\uc81c\ub4e4\uc744 \ud574\uacb0\ud558\ub294 \ub370\uc5d0 \uc775\uc219\ud574\uc9c0\uc2dc\uae38 \ubc14\ub78d\ub2c8\ub2e4.<\/p>\n
<\/body><\/p>\n","protected":false},"excerpt":{"rendered":"