{"trustable":false,"prependHtml":"\u003cstyle type\u003d\u0027text/css\u0027\u003e\n .input, .output {\n border: 1px solid #888888;\n }\n .output {\n margin-bottom: 1em;\n position: relative;\n top: -1px;\n }\n .output pre, .input pre {\n background-color: #EFEFEF;\n line-height: 1.25em;\n margin: 0;\n padding: 0.25em;\n }\n \u003c/style\u003e\n \u003clink rel\u003d\"stylesheet\" href\u003d\"//codeforces.org/s/96598/css/problem-statement.css\" type\u003d\"text/css\" /\u003e\u003cscript\u003e window.katexOptions \u003d { disable: true }; \u003c/script\u003e\n\u003cscript type\u003d\"text/x-mathjax-config\"\u003e\n MathJax.Hub.Config({\n tex2jax: {\n inlineMath: [[\u0027$$$\u0027,\u0027$$$\u0027], [\u0027$\u0027,\u0027$\u0027]],\n displayMath: [[\u0027$$$$$$\u0027,\u0027$$$$$$\u0027], [\u0027$$\u0027,\u0027$$\u0027]]\n }\n });\n\u003c/script\u003e\n\u003cscript type\u003d\"text/javascript\" async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS_HTML-full\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"MD","content":"输入一个 n×n 的二维数组 d,求是否存在一棵树,使得树上节\n点 i 和节点 j 之间的距离是 d(i,j)。"}},{"title":"Constraints","value":{"format":"MD","content":"n \u003c\u003d 2000\n0 \u003c\u003d d(i,j) \u003c\u003d 10^9"}},{"title":"Input","value":{"format":"MD","content":"n\nd(1,1) d(1,2) ... d(1,n)\n...\nd(n,1) d(n,2) ... d(n,n)"}},{"title":"Output","value":{"format":"MD","content":"若存在,输出 YES,否则输出 NO。"}},{"title":"Examples","value":{"format":"MD","content":"\u003cdiv class\u003d\"sample-test\"\u003e\n \u003cdiv class\u003d\"input\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Input 1\n \u003c/div\u003e\n \u003cpre\u003e3\u003cbr\u003e0 2 7\u003cbr\u003e2 0 9\u003cbr\u003e7 9 0\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"output\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Output 1\n \u003c/div\u003e\n \u003cpre\u003eYES\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"input\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Input 2\n \u003c/div\u003e\n \u003cpre\u003e3\u003cbr\u003e1 2 7\u003cbr\u003e2 0 9\u003cbr\u003e7 9 0\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"output\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Output 2\n \u003c/div\u003e\n \u003cpre\u003eNO\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"input\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Input 3\n \u003c/div\u003e\n \u003cpre\u003e3\u003cbr\u003e0 2 2\u003cbr\u003e7 0 9\u003cbr\u003e7 9 0\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"output\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Output 3\n \u003c/div\u003e\n \u003cpre\u003eNO\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"input\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Input 4\n \u003c/div\u003e\n \u003cpre\u003e3\u003cbr\u003e0 1 1\u003cbr\u003e1 0 1\u003cbr\u003e1 1 0\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"output\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Output 4\n \u003c/div\u003e\n \u003cpre\u003eNO\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"input\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Input 5\n \u003c/div\u003e\n \u003cpre\u003e2\u003cbr\u003e0 0\u003cbr\u003e0 0\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"output\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Output 5\n \u003c/div\u003e\n \u003cpre\u003eNO\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n\u003c/div\u003e"}},{"title":"Note","value":{"format":"MD","content":"在第一个样例中,符合题意的树有两条边:长度为 2 的 (1 - 2) 和长度为 7 的 (1 - 3)。\n在第二个样例中, d(1,1) 不能为 1。"}}]}